The present invention relates to a tracheotomy valve unit adapted for use with a tracheotomy tube inserted into a patient's trachea. More particularly, the invention relates to a tracheotomy valve unit containing a first valve that permits airflow through the valve unit when the patient inhales and blocks airflow through the valve unit when the patient exhales to enable speech, and a second pressure release valve that reduces intrathoracic pressure during expiration and improves comfort.
Individuals with tracheotomy tubes often have difficulty with speech, which is normally produced by airflow past the vocal cords on expiration. If a tracheotomy tube is present, air on expiration is mainly expelled through the tracheotomy tube rather than through the vocal cords. To overcome this problem, a one-way tracheotomy valve (or speaking valve) can be placed over the entrance to the tracheotomy tube. This allows air to be inhaled through the valve and into the tracheotomy tube, but does not allow exhaled air to escape back through the tracheotomy tube and out the valve. Instead, the air is forced around the tracheotomy tube, or through the shaft of the tube if it is fenestrated, and escapes through the vocal cords, permitting speech. The corresponding increase in subglottic pressure during exhalation also facilitates swallowing and cough production.
U.S. Pat. No. 4,759,356, Muir, issued Jul. 26, 1988, discloses such a one-way tracheotomy valve that prevents airflow except when the patient inhales. This is accomplished by positively biasing a flexible diaphragm against a valve seat using a rivet structure. The valve is thus entirely closed during the exhalation phase of the respiration cycle and at the beginning and end of the inhalation phase of the cycle.
U.S. Pat. No. 4,582,058, Depel et al., issued Apr. 15, 1986, discloses a tracheostoma valve assembly containing a spring-biased main valve that remains open during normal breathing and closes during normal air flow associated with speech. The valve assembly includes a separate external relief valve that is closed during normal breathing and speaking and opens to release air pressure resulting from a substantially increased air pressure within the valve assembly, such as due to a cough. The relief valve automatically closes when the air pressure is reduced in the valve assembly.
However, some people with a tracheotomy tube, particularly children, cannot tolerate a speaking valve because their airway is too obstructed by the tube to allow full and comfortable clearance of air inspired through the one-way valve. This may be caused by an upper tracheal or subglottic stenosis, suprastomal collapse, or too large a tracheotomy tube. These conditions limit the escape of inhaled air, and may result in a feeling of suffocation and raised intrathoracic pressure on expiration. This may cause the speaking valve to be displaced, or may result in chronically raised intrathoracic pressure which, in turn, may compromise venous blood return to the heart and predispose one to pulmonary hypertension.
Thus, there is a need for a tracheotomy valve unit that allows full and comfortable clearance of inspired air and prevents the build up of excess intrathoracic pressure during expiration, while maintaining sufficient pressure to allow the user to generate speech.